Investigating Glial Fibrillary Acidic Protein Expression and Cell Morphology in a Rat Brain Following Exposure to a Weak Electromagnetic Field and Nitric Oxide Modulation During Development

Background/Objectives: Nitric oxide (NO) and electromagnetic fields (EMFs) have been reported to influence central nervous system (CNS) function and organization. This study explores the effects of NO modulation and EMF exposure on neurodevelopment and glial fibrillary acidic protein (GFAP) expression and cell morphology, extending the prior work on perinatal EMF exposure in Wistar rats. Methods: Rats were perinatally exposed to water, 1 g/L L-arginine (LA), or 0.5 g/L N-methylarginine (NMA), along with a 7 Hz square-wave EMF at intensities of 0 nT, ≤50 nT, or 500 nT, starting three days before birth and continuing for 14 days postnatally. GFAP expression and cell morphology were analyzed via immunohistochemistry in regions including the hypothalamus, amygdala, hippocampus, and cortex. Results: Significant changes in GFAP morphology and expression are observed. A main EMF effect emerged in the right ventromedial hypothalamus, where the branch length of GFAP-expressing cells increased in EMF-exposed groups compared to the controls [t(32) = −2.52, p = 0.017]. In the hippocampus, LA exposure decreased GFAP expression in the right dentate gyrus compared to water controls [t(23) = 2.37, p = 0.027]. A sex-specific EMF effect was detected in the left CA2 hippocampus, where males exposed to EMF showed significant differences from unexposed males [t(15) = −2.90, p = 0.011]. Conclusions: These findings reveal complex interactions between EMF exposure, sex, and NO modulation, with region-specific effects on GFAP expression in the developing rat brain.